Differential gear for motor vehicles or the like



Dec. 5, 1950 A. J. BUTTERWORTH 2,532,757

DIFFERENTIAL GEAR FOR MOTOR VEHICLES 0R THE LIKE Filed Oct. 8, 1945 Patented Dec. 5, 1950 DIFFERENTIAL GEAR FOR MOTOR VEHICLES OR THE LIKE Archibald James Butterworth, Camberley, England Application October 8, 1945, Serial No. 621,117 In Great Britain October 9, 1944 8 Claims.

This invention consists of improvements in or relating to differential gears for motor vehic1es or the like and while the invention is applicable to various types of motor vehicle it has special utility in its application tothe steering of tracked or track-laying vehicles like caterpillar tractors, bull-dozers or tanks.

One object of the invention is to provide an improved differential gear in which a differential drive is effected by hydraulic means.

A further object of the invention is to provide a differential steering mechanism suitable for tracked vehicles.

The nature of this invention and of subsidiary features and the manner in which the invention `is performed will be appreciated from the following description by way of example of means for steering (or assisting the steering of) a tracked vehicle reference being made to the drawings accompanying the provisional specification in which:

Figure 1 isa diagram showing pump, valve and a developed or projected portion of the differental with oil conduits indicated in chain lines; and

Figure 2 is a section of the differential showing the actual arrangement of oil conduits there- The tracked vehicle is fitted with an oil pump driven by the engine or transmission and the resulting oil flow passes through a three-way control valve I2 with one outlet connected to a reservoir as indicated at I3, while the other outlet ports I4 and I5 lead'to the differential. In the developed portion of the differential in Figure 1, a planet pinion is shown at I6 engaging the driven gear wheels I'I. The shroud or lling member I8 (which substantially lls the spaces between the gears and approaches the teeth) has four pockets I9, 20, 2 I, 22 at the meeting points of the planet pinion I6 with the driven gear wheels The outlet port I4 of valve I2 is connected to the diametrically opposed pockets I9, 2|. The outlet port I5 of valve I2 is connected to the diametrically opposed pockets 20, 22. Thus if valve I2 is operated to open port I4 to the pump outlet, oil is pumped under pressure to pockets I9, 2|. Port |5 is then coupled by a transfer passage 4 to the reservoir I3. The meshing gears of the differential act as oil driven motors thus effecting differential rotation between the driven gear wheels Il and consequent steering through the tracks. Referring to Figure 2, the middle part of the shroud I8 appears in section but the arcuate portions lying between the driven gear wheels Il as indicated in Figure 1 are not apparent in Figure 2. The casing 23 which carries the planet pinions I6 closely embraces the gears. A crown wheel or worm wheel (not shown) is attached to casing 23 by flange and bolt-holes shown at outer periphery and is rotatably driven through the propeller shaft by a pinion or worm in the same manner as the crown wheel or Worm wheel in normal differential gears. An outer casing 24 is shown broken away. The pipe 25 from port I4 leads through annular channel 25 in casing 24 and through conduit 21 in half shaft 28 to chamber 29 in the shroud |8 and chamber 29 is connected to pockets I9 and 2| in the shroud. Similarly the pipe 30 from port I5 leads through annular channel 3| in casing 24 and through conduit 32 in half shaft 33 to chamber 34 in the shroud I8 and chamber 34 is connected to pockets 20 and 22 in the shroud.

If it is desired to steer to the left, as viewed in Figure 2, the control valve is turned so as to force oil through I4, 25, 26, 2l, 29 to pockets I9 and 2|. The oil pressure operates at the points of intermeshing of the pinions and gears to cause the left hand gear Il to turn more slowly and the right hand gear Il to accelerate relative to casing 23. This sets up a differential action between the half shafts 28 and 33 and turns the vehicle to the left. The oil passes from pockets 20 and 22 through 34, 32, 3|, 30, port I5 and transfer passage 4 to reservoir I3.

When the steering oil-pump is normally driven by the engine, the danger might arise that, in the event of the engine stalling whilst out of gear but with the vehicle in motion, the steering gear would be renderedineffective. To meet this eventualit the pump may be driven by the engine through a free wheel or ratchet and pinion, while being connected to the main propeller shaft or gear box output shaft by a suitable gear train and another free wheel device which idles until the engine stalls or drops below a predetermined speed, when it will take up the drive, thus ensuring that Whenever the vehicle is in motion there is a certain minimum steering power available.

The arrangement described is cheap, simple and effective. When a tracked vehicle is required to move straight ahead,`the differential may be locked by turning the valve to the neutral position in which it is illustrated in Figure 1. In this'position oil is not permitted to enter or leave the oil system within the casing 23, and since differential movement cannot take place without displacing oil, then, if any slight leakage is negmounted in and enclosed within said casing, gear wheels meshing with said planetk pinion and enclosed within said casing, a shroud member closely approaching the teeth of said gear Wheels and planet pinion and providing tw'o isolated chambers one on each side of the point of engagement of the pinion with a gear Wheel, means to force an oil circulation from chamber to chamber by Way of the meshing teeth to rotate the planet pinion about its own axis, thereby effecting the differential drive on the gear wheels, and means to reverse the direction of oil circulation.

2. AA differential gear comprising in combination a .rotatable easing substantially filled with eiland acting as a planet carrier, 'a planet pinion mounted in and enclosed within said casing, gear wheels meshing with said planet pinion and enelosed within said casing, al shroud member Aclosely approaohing the teeth of said gear wheels and planet pinion and providing a single chamber at each -side of eachpoint Vof engagement of the pinion with the gearwheels, means to force an `oil circulation from chamber to chamber by way of the associated teeth atl each point of engagement to cause rotation of the panet pinion in the same sense about its own axis thereby effecting'a differential drive on the gear wheels, and means f'or reversing the direotion of oil circulation.

3. A differential gear comprising in combinaltiona rotatable'easingI substantially filled with oiland acting as a V'planet carrier, planet pinions mounted (in and enclosed 'within said casing, gear `wheels meshing with said planet pinions and enclosed within the said casing, a shroud member closely approaching the teeth of said gear wheels and planet pinions and providing for at least i one .planet pinioma single chamber at eaoh side of the'poirit of engagement of the pinion with a Vgear wheel, means to io're an oil circulation 4from ohamber to chamber past the associated teeth at the point of engagement to cause the planet .pinion tourotate about its own a'xis, thereby effecting a differential drive on the gear Wheels and meansto reverse the direction of circulation between said pair pf chambers.

4. A d'iier'ential gear comprising in combinaeach side of Veach point of engagement of the pinion with the gear wheelsmeans to force an oil circulation past the associated teeth at each vpoint of engagement to 'cause rotation of the planet pinion .in the same 'sense about its own axis, thereby effecting a differential drive on the gear wheels, 'and means for reversing the direction of oil circulation.

5. A differential gear comprising in combinatlOIl rotatable easing Substantially filled With oil, drive means for said casing, planet pinions rotatable with said casing and gear Wheels meshing with said planet pinions, a shroud member closely approaching the teeth of said gear wheels and planet pinions and having four oil pockets at the meeting places of each planet pinion with the driven gear Wheels and alternativvel;7 a first diametrically opposite pair of pockets is connected to the inlet while the second diametrically opposite pair of pockets is connected to the outlet of the forced oil circulation or vice versa, so vthat the planet pinion may be forced to rotate on its own axis in one sense or the other.

'6. In a motor 'vehicle a differential gear comprising in combination a rotatable carrier containing planet pinions, gear wheels meshing with sai'd 'planet pinions, a casing substantially lled with oil in which said gear wheels and planet pinions are enclosed, a shroud member closely approaching the teeth of said gear Wheels and planet pinions and providing for at least one planet pinion, twoisolated chambers one on 'each side of at least one of the points of engagement of the pinion withy the gear wheels, an ,oil pump Viilled with oil and rotational drive means therefor, a carrier containing planet pinions Within said casing and, rotatable therewith, gear wheels within 'said casing 'and'meshing with said pinions, a shroud member closely approaching kthe teeth of said gear wheels and planet pinions but leaving four oil pockets at the meeting places of each Aplanet pinion within the driven gear wheels, an

V'a shroud member closely approaching the teeth of said gear Wheels an'd planet pinions, but leaving 'fo'uraoil pocketsat the meeting places of each planet'pilfl'on With the ilVe'rl Vge''l Wheels, an Oil pump driveniro'ma moving part of said vehicle Vand a valve connecting said pump to diametrically opposed pairs of said oil pockets, or to the oil reservo'insaid valve being operatively connected to a steering central. ,A A v 'ARCHIBALD JAMES BUTTERWORTH.

"FRNS' ITD Ehe following references are of record in the le of this patent:

NITEVD V'S PATENTS Nain-e Date 1,099,161 Brown June 9, 1914 1,266,712 Reagan May 21, 1918 2,400,728 Akers May 21, 1946 

